This invention relates, in general, to electronics, and more particularly, to semiconductor components and methods of manufacture.
Semiconductor devices manufactured in a semiconductor wafer according to a process described in U.S. Pat. No. 5,557,149, issued on Sep. 17, 1996, eliminate the need for a leadframe. These devices can be packaged at wafer level before the individual devices are sawed apart or otherwise singulated from the wafer. The wafer level packaging process includes stencil printing an encapsulant over the semiconductor wafer, using centrifugal forces to eliminate air pockets in the encapsulant, attaching a capping wafer to the semiconductor wafer, and curing the encapsulant.
However, this wafer level packaging process has several problems. First, the centrifugal process does not eliminate all of the air pockets or voids from the encapsulant. The voids are commonly formed above the semiconductor wafer and in isolation trenches etched into the semiconductor wafer. The severity of this void formation problem increases with larger diameter wafers. A second problem stems from the thickness of the wafer-encapsulant-cap assembly or structure being non-uniform between different wafers and within the same wafer. The lack of thickness control produces the unacceptable thickness variations. Third, the wafer-encapsulant-cap assembly often warps because of the high stress levels in the assembly. This problem is also intensified in larger diameter wafers and after thinning the device wafer during the later stages of processing. Inconsistent thicknesses between the wafer-encapsulant-cap assemblies and thickness variations within a single assembly can significantly impact the warpage of the wafer-encapsulant-cap assembly. The assembly warpage causes handling and processing problems. A fourth problem stems from the poor adhesion between the encapsulant and the wafer, which produces poor reliability.
Therefore, a need exists for a semiconductor component and method of manufacture that eliminates voids in the encapsulant, that uniformly controls the thickness or height of the semiconductor component, that does not produce warped wafers, and that has improved adhesion between the encapsulant and the wafer.